A milling tool used in a milling process for a workpiece generally includes a plurality of cutting inserts. In order to more evenly finish a processed surface of the workpiece, it has been known that at least one of the cutting inserts (indexable inserts) is configured to have a wiper edge (an indexable insert with the wiper edge) protruding toward the workpiece relative to a flat cutting edge of other cutting insert, as in a milling tool disclosed in Japanese Unexamined Patent Publication No. 2001-138122 (Patent Document 1).
In the milling tool disclosed in Patent Document 1, the wiper edge is an approximately straight line shaped cutting edge or an approximately arc-shaped cutting edge having a large radius of curvature. In this case, during the milling process in which the workpiece is subjected to repetitive cutting by the cutting insert with the wiper edge, there occurs a large overlapping area between a rotation locus of the cutting insert with the wiper edge that precedingly cuts the workpiece, and a rotation locus of the cutting insert with the wiper edge that succeedingly cuts the workpiece. Therefore, a chip cut by the wiper edge may have an excessively small thickness. When the chip has the excessively small thickness, the processed surface of the workpiece may be roughened as being gouged out, and a finished surface state may be conversely deteriorated.
The present invention has been made in view of the above problem, and aims at providing a cutting insert capable of improving the finished surface state by reducing occurrence of gouge phenomenon, as well as a cutting tool, and a method of manufacturing a machined product.